Non-aqueous aerosol foams have been disclosed heretofore. The selection of suitable foaming agents has however been a problem. U.S. Pat. No. 3,135,658 to Hanus and Oulette, discloses a method of treating bovine mastitis using a milk miscible, non-aqueous surfactant stabilized oleaginous liquid material, which foams upon contact with the milk in the cow's udder. The material which is administered does not, of itself, create a foam. A heat generating composition, one of the uses of the foams disclosed herein, is disclosed in U.S. Pat. No. 3,250,680 to Menkart and Ricciuti. This material is not a foam but utilizes aluminosilicate molecular sieve materials taken up in non-aqueous carriers such as polyethylene glycol, using sorbitan monostearate or polyoxyethylene sorbitan mono oleate as surfactant materials in the composition.
The first true non-aqueous aerosol foam is disclosed in U.S. Pat. No. 3,419,658 to Sanders. The Sanders foam however is limited to white mineral oil as the anhydrous liquid. The surfactants are also rather limited to their particular category. It should be noted that the same author published a somewhat extensive review of non-aqueous aerosol foams in Soap and Chemical Specialties, November 1960, page 87 through 109. White Sanders projects several uses for such materials, the non-aqueous liquids are limited to alkylene glycols and the ethers thereof. Furthermore, the surfactants are similarly of the propylene glycol monostearate or polyoxyethylene sorbitan monostearate type.
U.S. Pat. No. 3,770,648 to Leonard Mackles (one of the inventors herein) is directed to an aerosol foam utilizing a silicone resin as the foaming agent. U.S. Pat. No. 4,379,143 to Sherry, et al., is directed to a topical self-heating liquid or ointment used for analgesic purposes which comprises a zeolite and an anhydrous liquid. There is no disclosure in Sherry of the possibility of foaming the compositions since no foaming agent is disclosed. Furthermore, the invention is specifically limited to the use of the zeolite as the sole warming agent. U.S. Pat. No. 4,627,973 to Moran, et al., is directed to a skin mousse. Moran, et al., however comprises a substantial amount of water and cannot therefore be considered to fall within the category of the present invention.
U.S. Pat. No. 4,639,367 to Leonard Mackles is directed to an edible anhydrous aerosol foam composition comprising a foamable liquid oil, a dispersed solid, a foaming agent and a propellent. However, the disclosure of this invention being directed to edible foams, does not consider the requirements necessary for foaming a topically absorbable, as opposed to an ingestible, anhydrous liquid.
U.S. Pat. No. 4,752,465, which is a continuation-in-part of the aforementioned U.S. Pat. No. 4,639,367, is directed to a similar product having dispersed therein a particular proportion of solid particles.
It will thus be seen that the problem of providing an anhydrous topically applicable aerosol foam containing a foamable topically absorbable anhydrous liquid, has not been satisfactorily addressed by the prior art. In order to provide commercially satisfactory products in the aforementioned category, it is necessary that foams be preparable from a diverse group of anhydrous liquids such as glycerol fatty acid esters; e.g., soybean oil, corn oil, mono and diglycerol esters, acetylated monoglycerides, glyceryl triacetate; di and triethyl esters of organic acids, e.g., triethyl citrate, diethyl phthalate; aromatic acid esters, e.g., methyl salicylate, benzyl benzoate; and water soluble glycols, e.g., propylene glycol sand polyethylene glycol 400.
While the art, as shown by the aforementioned references, teaches a large number of foaming agents, it has been our surprising finding that these foaming agents are not satisfactory for foaming all of the aforementioned anhydrous liquids.